Pressure sensors are used to detect the pressure or even the differential pressure in corrosive measuring environments. For example, the pressure determination upstream and downstream from a soot particle filter may be cited as a typical application from the automotive sector. The differential pressure may be used to determine the load of the soot particle filter and regulate the filter burn-off.
In corrosive measuring environments, it is preferred to use sensor elements that are exclusively made of media-resistant materials. In this case, the printed conductors and terminal pads are usually made of gold. To make it possible to implement at least the evaluation electronics according to conventional methods using less expensive materials such as aluminum, the evaluation electronics are situated in an area of the sensor housing into which the measuring medium is unable to penetrate. This housing area for the evaluation electronics is separated off using a separating wall fastened in the housing interior.
The electrical connection between the sensor element and the evaluation electronics in the two housing areas separated from one another is implemented in actual practice using a ceramic carrier having media-resistant printed conductors. The ceramic carrier is situated on the housing floor together with the sensor element and the evaluation electronics. The contact between the terminal pads of the sensor element and the printed conductors of the ceramic carrier is made by media-resistant bonding wires, while it is again possible to make the connection to the evaluation electronics using aluminum wires and aluminum bondlands due to the media separation within the housing. The separating wall, which extends to the housing cover and is or will be connected to it, is then bonded to the ceramic carrier between the sensor element and the evaluation electronics.
In actual practice, this type of electrical connection between the sensor element and evaluation electronics has proven to be very complex and subject to error, as it requires a ceramic carrier provided separately with media-resistant printed conductors and bonding wire connections, on the one hand between the sensor element and the printed conductors and on the other hand between the evaluation electronics and the printed conductors. To that end, the ceramic carrier must first be placed, adjusted and fastened within the housing in order to be contacted later in additional method steps using bonding wires.